Johnstone is set to make his first return to Old Trafford since leaving to join the Baggies in 2018 this weekend and he is set to face a number of familiar faces.
“We still keep in contact now. He did message me last year and he said 'I want to see you in the Premier League'. It's nice to get messages like that," Johnstone told WBA TV.
“Just watching him every day. In the gym, just around the place, training. Before games, when we travelled, he was very relaxed and confident in his own ability, and obviously very good.
“In warm-ups, watching him, you can't get much better from that. I was learning from him every single day. He's a good person."